


The Mad King's Rut

by San121



Category: Fate/Grand Order
Genre: Also I am too, Anal Sex, Basically Cu Alter is a Breeder because Medb is a thirsty hoe, Come Inflation, Double Penetration, Explicit Sexual Content, F/M, Minor Violence, Vaginal Sex, dog dicks
Language: English
Status: Completed
Published: 2019-02-26
Updated: 2019-02-26
Packaged: 2019-11-05 20:51:32
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 6,182
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17926139
Author URL: https://archiveofourown.org/users/San121/pseuds/San121
Summary: Cu Alter has a Rut due to Medb's wish on the Holy Grail. After dealing with the first Rut, Ritsuka tries to better prepare for the second Rut. Cu, however, has an idea of what he wants, but won't confess.





	The Mad King's Rut

When Medb casually mentioned that “her” Cu has a rut to Ritsuka, the young Master nearly combusted from embarrassment. While the other three Cus were handsome, there was something about the Berserker that drew Ritsuka to him, to a point where she feared she was annoying him with her presence. Her embarrassment turned into to fear when Medb commented on how it should start within the week, leaving the Master to flail about and try to set up everything that Cu would need during his rut. Upon confronting him about it, Cu looked down at Ritsuka with mild surprise.

“I just need water, food, and something to curl into,” Cu explained, ignoring a sputtering Medb, who had just “offered” to help him through his heat. Ritsuka nodded, not really thinking about how the word “rut” implies the need for sexual release, instead thinking of how she could minimize the tension between Servants in Chaldea while Cu is in rut. The five days of his rut had been hard, with Ritsuka diverting some of the Servants from Cu’s room (namely Medb, who was trying to get in to “help”, and the other Cus, who liked to see if they can over power their Berserker form individually) while still working to gather materials and Saint Quartz. Every two or so hours, she would knock on the door and ask if Cu needed her to drop something off outside his room. Sometimes he would answer (usually telling her no), while other times he was moaning and growling enough for Ritsuka to flee to her own room to relieve herself. Once his rut had finished, Ritsuka and Romani both asked Cu for more information on his rut, planning for the future as to not be caught off guard.

“Once every two months, for five to seven days. I’ll be more irritable. Don’t talk to me more than needed during the two days before. The check ups help ground me,” Cu listed, monotone and blank as both Master and Doctor write the information down.

“And a rut partner? Would that help too?” Romani asked, causing Ritsuka to flush. Cu tilted his head and shrugged while nodding.

“It helps a little. Just don’t want one,” he answered.

* * *

Ritsuka frowns at the calendar, noticing the day creeping closer. Just a week away from when Roman and Cu estimated his next rut would be and there is still a good deal to do. Warnings to put out (apparently Asterios became “friends” with Cu during the past two months, as the Berserker often sits happily beside the Mad King, despite the confusion and fear of the younger Servants and Master), restrictions to set up (Medb), and egos to start soothing should things go south (Gilgamesh and Merlin are both _very_ interested in the idea of a Servant with a rut). Tapping her thumb to her fingertips, she calculates what she needs and how much she needs based off what was pulled out after his first rut.

“15… no, 17 sheets… 20 pillows… 4 of those big comforters…” she mumbles, wandering down the hall as she thinks of what he would need for his bedding. Pausing in the middle of the hall, she blinks and cocks her head.

“Would he want it to smell like someone?” she wonders out loud, tapping at her chin in thought.

“Of course he would! That’s why I’m giving him _my_ clothes!” Medb cries behind Ritsuka, startling the Master. Leaning against the wall, Ritsuka tries to calm her heart before turning to scold Medb, only to choke on her own spit. Medb stands before her, looking down her button nose at the Master, completely naked save her crown, while carrying what Ritsuka can only assume is a bundle of clothes and sheets that Medb wore or curled up in. Sputtering, she flips one of the sheets over the Rider, looking around the hall to make sure no one else sees the very naked woman. Ushering Medb out of the hall and into one of the spare rooms, Ritsuka crosses her arms and huffs, attempting to look intimidating.

“You aren’t giving him anything for the time being, Medb,” Ritsuka tells her, flinching a little at the glare she gets from the Servant. Medb straightens her posture, thrusting her naked breasts into Ritsuka’s face, causing the girl to sputter and flush in embarrassed/confused arousal.

“And why not?” Medb demands, puffing up her cheeks with displeasure as she watches her Master sputter and flail about.

“Cu s-said he d-doesn’t really want a rut partner. P-please respect his w-wishes,” Ritsuka manages to stutter out, pointedly looking away from Medb. The Rider whines, stomping her foot and glaring at the Master.

“But he can still have my sheets!” Medb whines, shaking her fists and causing her breasts to jiggle up and down. Ristuka sputters, looking up at the ceiling while trying to avoid touching the naked Rider.

“He also is very against dealing with you, Medb! You know this!” the Master scolds, staring intently at the tiling of the ceiling. Medb huffs, knowing that the other woman is correct but not wanting to acknowledge it. Ritsuka swallows, still flustered but willing to help her Servants interact “civilly”, she offers, “I was heading toward Cu’s room, so I can ask him if he wants your sheets.”

“That will suffice,” Medb concedes after a moment, nodding and turning to leave the room. Ritsuka squeaks, managing to sputter out, “Please put on clothes!” before Medb is truly out of ear shot. Once left alone, Ritsuka focuses on calming her nerves and hormones, taking deep breaths until she regains control of her body. Once back in control, Ritsuka heads back out, into the hall, only to run head first into Cu. Stumbling back, she blinks in surprise before looking up with wide eyes.

“What?” he snaps, glaring down at her. Ritsuka squeaks as a reply, stumbling back away from him. Cu raises an eyebrow, his eyes never leaving her as she makes a fool of herself.

“I-I was looking for you,” she squeaks. Pausing to clear her throat, she continues, “What do you want for your bed during your rut? Last time, we managed to grab you a good amount of sheets, pillows and comforters, but now we have more time and a better warning. So, what do you want?” Cu stares her down, tilting his head to the side. The silence between them stretches uncomfortably, making Ritsuka shift nervously and avoid Cu’s gaze.

“Mostly pillows and comforters. A few sheets, but more pillows and comforters,” he finally tells her. She snaps her head toward him, perking up at having the information she was looking for.

“Oh! So, how many more pillows and comforters? You had about twenty pillows last time and only four comforters. Maybe twelve comforters and another ten pillows? Would that be enough?” she asks, bouncing a little on the balls of her feet. Cu scowls at her, but still nods, glaring as she mumbles about preparation and what needed to be gathered. Abruptly she stops and turns back to Cu.

“Do you want the pillows and stuff to smell like someone? I read somewhere that familiar scents can help during the, um, rut and heat of animals,” she asks, her face flushing again. The Berserker stills, looming over her with the intensity of his stare. Slowly, the color fades and drains from her face as she curls in on herself while trying to maintain eye contact.

“…Your scent. If any scent is to be in my…nest, it will be yours,” Cu growls, glaring at her. Ritsuka blinks at his reply, squeaking out, “Oh, okay.” Cu nods at her before storming down the hall, leaving the Master to stand alone in the hall.

* * *

6 Days until rut

 

Ritsuka is talking to EMIYA about food for Cu and his rut. Although reluctant, EMIYA seems to be agreeing with what to provide for the Berserker while offering some alternatives for the foods that would be too messy/too much of a hassle for someone not thinking straight.

“Will that work?” she asks, pulling on her lower lip in thought. EMIYA sighs, gently grabbing her wrist to stop the abuse on her lip.

“Yes, it should work out fine. Please calm down, Master,” he assures her. Ritsuka nods idly, blinking when she sees Cu prowl down the hall toward them.

“Oh, Cu! We were just talking about the food for your rut! Is there anything you want in particular?” Ritsuka asks, looking up at the Berserker earnestly. Cu blinks down at her slowly, before looking up at the Archer.

“Meat, fruit, and water,” Cu states, shrugging before shoving his way between EMIYA and Ritsuka, his tail lashing out to hit the Archer on the shins. EMIYA curses, stumbling back from the collision while Ritsuka gasps and turns to Cu.

“Why did you do that, Cu? You could have gone around us,” she calls at his retreating back. Cu pauses and looks over his shoulder, his glare flicking between EMIYA and Ritsuka.

“He was too close,” he growls, turning away from them and storming down the hall, scaring Ibaraki-Douji with a loud growl. Ritsuka frowns, her hands resting on her hips.

“But he could have just walked around,” Ritsuka huffs with frustration. EMIYA gives her a deadpan stare, squinting a little after a moment when Ritsuka looks over at him for a comment or an explanation.

“…Oh, you’re serious,” EMIYA says, sounding a little surprised. Ritsuka cocks her head to the side while EMIYA sighs and rubs at his eyes.

“Anyway, I’ll take care of his food. Please come get it for him,” the Archer requests before entering the kitchen, leaving Ritsuka to stand baffled in the hall.

* * *

4 days until Rut

 

Ritsuka hurries down the hall, biting her thumb nail nervously as she heads toward the library. After explaining why Asterios can’t hang around Cu for a week or so, she asked if he knew where Merlin and Gilgamesh. The large Berserker pointed her toward the library, only for her to over hear Artoria huffing about how the Caster and Archer are planning something. Arriving at the library, Ritsuka enters only to stop abruptly in mild fear. Cu is sitting on the couch, glaring at the two Servants currently chattering about how his rut is affecting him, keeping him bound with the Chains of Heaven.

“…meaning that it would fade if he manages to impregnate someone,” Merlin states, before blinking and smiling at her. Gilgamesh turns his head and raises an eyebrow, smirking at Ritsuka.

“What,” Ritsuka starts carefully, glancing at Cu trapped on the couch, “are you two doing?” Merlin smiles innocently while Gilgamesh huffs out a laugh. The Archer takes a step forward, catching her face to make her look up at him.

“Nothing you need to worry about, Master. Instead, let’s talk about how you should just agree to become one of my treasures,” he orders. Sighing, Ritsuka takes a step back and shakes her head, looking up at the Archer, completely unimpressed.

“I’ve told you, multiple times over, that I don’t want to become a treasure,” she huffs, crossing her arms under her chest. Gilgamesh pouts while Merlin laughs a little nervously and shifts closer to Ritsuka.

“Now, Gilgamesh, it’s important to remember that Master is her own woman. If she agreed to be with anyone, it would be someone who acknowledges her strength and adds to it,” Merlin explains, patting at Gilgamesh’s shoulder. The Archer scowls, glaring at the Caster before glancing over his shoulder at Cu. At the look that crosses Gilgamesh’s face, Ritsuka rocks up on the balls of her feet to try to get a glance of Cu, only to huff upon realizing that she’s too short. Rolling back down, Ritsuka sighs, deciding to focus on making the duo leave Cu alone.

“If you have any more questions about Cu’s rut, please hold them until after it’s passed. Now, please let him go,” she orders, resting her hands on her hips. Merlin smiles at her while Gilgamesh seems uncertain about something.

“Don’t worry, Master. We were just about to release Berserker Alter,” Merlin tells her. Raising an eyebrow at him, Ritsuka crosses her arms under her chest again, deadpanning, “Don’t lie.”

“Ahahaha… You’re not wrong,” Merlin shakily admits, his hair fluffing out like Fou when it realizes someone it doesn’t like is looking at it. Ritsuka frowns, slowly raising her command spells up, looking at both Servants murderously.

“I’m about to use a command spell for something stupid, and you both know how I don’t like doing that. So, let Cu go before I make you both regret forcing my hand, okay?” she threatens, cocking her head to the side and giving them a bright smile, her killing intent still pouring from her. Gilgamesh leans back, looking irritated, while Merlin laughs nervously.

“Yes, yes, we’ll be going. Archer, if you could?” he assures her, turning to his partner in crime. Sighing, the Archer snaps, dispersing the Divine Chains from the room.

“Very well. However, I ask for recompense on your behalf, Master,” Gilgamesh orders, once again catching her face in his hand. Sighing, Ritsuka raises an eyebrow, maintaining eye contact with the Archer.

“What do you want,” she intones. Gilgamesh smirks and leans down, bringing their faces closer together when something catches his eye and he pulls back, barely dodging a large spiked tail that swiped at his face. Ritsuka jumps, squeaking when she bumps back into a chest and gloved arms wraps around her.

“Back off,” Cu growls from over her head, probably glaring, even though she can’t look up to see due to his chin pressing down on her head. Both Servants do as Cu demands, although Gilgamesh glares back at the Berserker. After a glare-off, Gilgamesh scoffs and strides out of the library, Merlin following with a teasing smile. Ritsuka sighs, trying to pull away from Cu only for the Berserker to growl and tighten his grip around her.

“Cu? What’s wrong?” she asks, trying to look up at the Servant. Cu huffs, nuzzling against her head before abruptly letting her go and storming out of the library, leaving the Master confused in the library.

* * *

3 Days until Rut

 

Rubbing at her temples, Ritsuka frowns at the gathered Cus before her. Proto is currently nursing a rib and a large bruise has appeared on his cheek while Lancer grins up at her crookedly, putting more weight on one leg than the other. Caster smiles up at her from his spot on the floor, his wolves curled around him, altering between whining pitifully at her and growling at Berserker, who is the only one of the four to be unharmed.

“Why? Just, why?” she sighs, covering her face with her hands.

“Well, we wanted to get one more try in before his rut hits, Missy!” Lancer answers easily, practically beaming at her. Ritsuka groans, covering her face again, even as the wolves creep over to her for pets and comfort after the fight. Reaching down to pet the animals, Ritsuka gave the Cus a look of disappointment.

“I told you three about his rut to avoid any of you from starting a fight while he’s high on hormones. It’s more likely going to end in death than victory for you guys,” Ritsuka scolds the two Lancers and the Caster. She turns to the Berserker with a frown, pointing at him.

“And you were the one who told me to keep people away from you. I know that they are your other selves, but that means you should have been able to tell them to leave you alone,” she huffs. Cu clicks his tongue and turns his head away. Proto whines, wobbling over to her and draping himself over her shoulders.

“But, we wanted to spaaaaar,” he drags out the vowel, resting his chin on her head. Ritsuka huffs, rolling her eyes as she scratches behind one of the wolves’ ears, an exasperated smile crossing her face.

“Then go spar with Fergus or EMIYA-kun,” she tells him, laughing at the whine that the youngest Cu releases into her shoulder. A low growl startles them, causing the duo to look over at the Berserker. He stops growling, but he is scowling at the pair, or more accurately the Lancer draped on her.

“Get off her,” he demands, rising from his relaxed seat to tower over the pair. Proto swallows loudly in Ritsuka’s ear before moving off her, his hands raised submissively. Ritsuka huffs, frowning at Cu while crossing her arms.

“What’s wrong with you? Just because you’re nearing your rut doesn’t mean you can be mean to others,” she scolds, swallowing nervously when he growls at her again. Sighing, she shakes her head before motioning Proto to follow her.

“I’m going to help Cu get to the infirmary before sending someone to come help you all,” she tells them, supporting Proto before leading him out of the room. Once to door closes behind them, inside the room, both Lancer and Caster turn to look at the Berserker.

“You really should just tell her,” Caster sighs, petting his wolves that return to their master. Lancer snorts, jerking his thumb at Berserker.

“He’s us. Would we tell her?” Lancer points out. Berserker growls and storms out of the room while Caster nods sullenly in agreement with Lancer.

* * *

Day before Rut

 

Shuffling down the hall, Ritsuka peeks over the mountain of comforters and pillows as she struggles to get to Cu’s room. Fou’s chirps and coos before her helped a bit, allowing her to navigate around anything a Servant may have left in the hall way, but still the amount of comforters and pillows make the walk difficult.

“I need to work out more,” she groans, hefting the comforter and pillows up again. Fou chirps from in front of her, almost like it’s laughing at her. Huffing, she sees that she’s in front of Cu’s room. Kicking the door lightly, she shifts the material in her arms as best she can to smile when Cu opens his door.

“Hey, Cu! I got all the comforters and pillows you asked for along with one of my coats. Is there anything else you need?” she asks. Cu stares at her before stepping to the side, motioning for her to enter his room. Confused, she enters the room, waddling over to the bed to set down all the materials she is carrying.

“Alright, that should be all of it,” Ritsuka huffs, quickly thumbing through the comforters to make sure she brought the right amount before turning to give Cu another smile. She pauses, blinking when he stands in front of his door, staring at her while breathing heavily from his mouth.

“Cu?” she cautiously says, taking a step closer to him. He inhales sharply, his pupils blown out as his tongue lulls out, reminding Ritsuka of Caster’s wolves.

“Can I… hold you…” he pants, his eyes never leaving her. Slowly, she nods, looking for some sort of explanation for Cu’s shift in behavior. The Berserker steps into her personal space, pushing her back to sit on the bed before getting on his knees, settling between her legs. A low purr rumbles from his throat as he nuzzles against the meat of her thighs, massaging the opposite leg. A flush creeps up her face while a low heat begins to pool in her lower abdomen, drying her mouth as Cu presses his nose against her thigh and inhaling loudly.

“Smell so good, Master. Delicious,” he praises, rubbing his face against her tight covered thigh before frowning and growling. Ritsuka tenses, waiting for him to snap at her, instead she jumps in surprise when he tears her tight enough to expose a patch of skin for him to press his cheek and nose against. He sighs happily, closing his eyes and nuzzling against the patch.

“Cu? A-are you okay?” she ask, hesitant to touch him. Red eyes open to look up at her, before he turns his face slightly, maintaining eye contact as he mouths at her thigh. Squeaking, Ritsuka tenses as he nips and sucks at the spot, moaning loudly.

“You need to leave, before it really sets in,” Cu gasps, his voice low and reluctant but still firm. Ritsuka blinks before realizing that his rut came slightly earlier than anticipated. Biting her bottom lip, she gently, carefully grasps his face, pulling his face away from her thigh to look him in the eye.

“Is your rut setting in?” she asks, just for clarification. He nods, whining as he seems to be conflicted between pulling his face away to go back to her thigh or staying where he was as she gently rubs her fingers against his cheeks and behind his ears.

“Do you want me to stay with you?” she asks, watching as his pupils dilate enough to just leave a ring of red around them. He swallows against her hand, licking his lips as he stares up at her.

“If you stay with me here, I’m going to fuck you continuously. There will be a few pauses between, but it will mostly be me fucking you into my nest,” he warns, clinging to his mind just long enough to give her a chance to escape. Swallowing her nerves, Ritsuka takes a calming breath.

“I-I’m a virgin, s-so just go easy on me first, o-okay?” she requests, feeling the heat cover her cheeks as she squeezes her eyes shut. She feels Cu still against her hands before he leans forward to nestle his face directly between her legs, causing her to gasp and snap open her eyes. The sound of tights ripping reach her ears before she feels the chill of the air on the inside of her thighs, watching as the thin, black material is pulled down her legs, stopped only by her boots.

“You should have been more careful, Master,” Cu purrs, licking against her panty-covered entrance. Squeaking, Ritsuka covers her face, peeking down at him through her fingers as he massages her thighs and continues to lap at her through her panties.

“W-what do you mean b-by that?!” she cries, squeaking again as Cu forces her to lose her balance and fall back on the bed, her upper back and neck supported by the comforters and pillows she brought in. He looms over her, licking his lips again as his blue hair falls over his shoulders.

“To tell a man that he is your first can give him a lot of power over you,” Cu growls, leaning down to nip at her neck while undoing her shirt. His hands grope her breasts roughly once he finishes, marking them with bites and harsh sucks, grinning at her gasps and moans.

“Ah, b-but,” Ritsuka gets cut off when Cu pulls off her boots, the remains of her tights, her underwear and skirt in rapid succession, leaving her naked on his bed. Cu growls again, hefting her legs over his shoulders to dive down at her vagina, licking and suckling. Ritsuka gasps, arching against his mouth while he opens her carefully with his tongue, rubbing her clit with his thumb.

“So tasty… Smell so good…” Cu moans against her opening, lapping and purring against her. Hearing a steady thudding, Ritsuka peeks over Cu’s shoulder to blink at his wagging tail. Suddenly, Cu pulls her against his chest, panting harshly over her head while one of his arms quickly arranges the comforters and pillows, as if he just remembered that the material was there.

“Needs to be perfect,” he growls, pinning her to his chest with his tail to use his other arm to finish. Ritsuka tries to focus on her breathing, however, from where she is pressed against him, she smells cinnamon and smoky wood. Her mouth waters and her vagina clenches, moaning at the scent before pressing her mouth against his skin. The growl Cu lets out causes Ritsuka to stop and flush again, about to lean back when his tail, careful of the spikes on it, lifts her enough for Cu to kiss her. He pushes his tongue into her open mouth, growling and moaning into her mouth just as eagerly as she moans and whines into his. Pulling away, Cu catches her lip with his teeth, cutting it open enough for him to lick up some blood off her mouth and chin.

“You taste so good, Master,” He purrs, laying Ritsuka in the nest he made before undressing himself. Ritsuka squeaks again, feeling herself blush brightly at the sight of Cu’s naked body. She knew Medb is into some weird sex things, but actually seeing them is a whole different thing.

“Wh-what’s with your, um,” Ritsuka stumbles, staring wide eyed at his groin. While she knew what a penis looked like (she’s a virgin, not a prude), to see not only two penises but also how thick and long they are combined with a bump at the base and a tapered top that leaves her somewhat concerned. Cu chuckles, licking his teeth while grasping her ankles to lift her legs onto his shoulder.

“These are based off wolf-cocks. Medb made me an ultimate breeder, perfect for impregnating and pleasuring women,” he answers, so far gone in his own lust to be reluctant to part with such information. Ritsuka inhales sharply as he rubs both his cocks against her mound, her face matching the markings on Cu.

“One will go in your ass while the other parts your cunt, filling you completely,” he rumbles, leaning down to nip at her tit. She yelps and jolts her head back, arching into his mouth as he suckles on her nipple while still rubbing against her. Despite her own curious explorations with her hands, Ritsuka feels overly sensitive under the Berserker, feeling her slick drip from her entrance and over her asshole. Obviously getting impatient, Cu rests her ankles on his shoulder to line up his cocks, prodding gently at her ass and pussy.

“Deep breath, Master,” he orders, watching her inhale sharply. He rubs her stomach while commanding, “Now exhale.” She obeys, releasing her breath only to choke at the feeling of him pressing in slowly. He pauses at the feeling of her hymn, leaning down to kiss her harshly, biting her lips to release more blood. Despite the small amount of pain, Ritsuka moans at the taste of iron that Cu pushes into her mouth with his tongue. His clawed hands find her breasts, squeezing and pulling at them rhythmically, dragging gasps and whines from her, before he pushes past her hymn.

“Aaah!” she cries, tears gathering in her eyes at the pain, clenching down tightly around the protrusion of both her cunt and her ass. Cu pauses again, trembling himself, before he licks up her tears and licks at her still bloody lips, cooing wordlessly at Ritsuka until she breaths regularly.

“I’m moving,” he tells her before slowly starting a soft rhythm. Ritsuka hisses at the raw feeling in her ass and the small, sharp points of pain in her vagina, clawing at the materials beside her head. Cu releases a rumbling purr, pumping in and out of her slowly and softly, digging his claws into the comforters under Ritsuka. Slowly, the pain is out matched by pleasure, leaving Ritsuka breathless at the feeling of fullness. Shyly, she locks her ankles around Cu’s neck, grabbing his forearms and pushing back against him when he thrusts forward. They gasp in tandem, Ritsuka clenching around his cocks, just shy of his knots. Cu growls and picks up his speed, grinning at the mewls and moans Ritsuka begins to make.

“So pretty… Feels so good… My Master…” He growls, leaning down and nuzzling at her shoulder, grinning at the whine she gives due to the pull of her thighs from where he presses them against her.

“Cu, Cu, oh God,” she moans, pushing against his knot again. He snarls and thrusts hard against her, grinning at her scream of pleasure when his knots finally push in and against her g-spot. He feels her orgasm around his cock, overly sensitive and unused to sex making it so easy for him to drag her to release.

“Good girl,” he praises, rocking his inflating knot in her openings, grinning and purring at the over sensitive twitches she gives his cocks. He slowly picks back up, watching to make sure she isn’t in pain from over stimulation, before pressing against her hard. His eyebrows go up when he looks down to where they are connected and he can see his cock outlined.

“Holy shit. I can feel… You’re against my womb,” She gasps when he rocks forward again. Something snaps in Cu, leading him to snarl and rock harder against her, working his knot until he feels his release coming. Roaring, he drops down and bites her shoulder as he fills her womb and stomach with his cum, feeling her inflate from the amount within her. She screams again before it trails off to a moan, her hands running up his arms to fall over her thighs, petting her now protruding abdomen.

“Oh, God. So full. Gonna get pregnant,” she whispers, her thighs and legs tremble against his shoulders. He lifts his upper body, gently pushing her legs off his shoulders to allow them to fall around his waist.

“Good. Make you mine. Only mine,” Cu growls softly, petting her inflated abdomen. She moans at the feeling, her head falling back while his tail wags lazily. He carefully shifts them, pausing at each whimper to sooth her pains from the pull of his knots, until she can lay on top of him, keening at the feeling of the cum being pushed towards her still plugged holes.

“So good for me, Master. Make you feel good,” Cu promises, his rut starting to settle in as it shuts down his communication to focus on his mate and his base instincts. Ritsuka whines, stretching her neck up to press a kiss to his chin. With a growl, Cu leans down to properly kiss her, groping her ass, pulling gasps from her as his slowly softening cocks twitch in interest. The knots finally deflate, letting his cum gush out of her with a gasp. Ignoring the liquid, Cu grasps her hips and starts forcing her to ride him. He purrs loudly as she scrambles to find her footing before helping ride him. His tail, originally laying to the side to allow him to rest on his back, lifts to lightly trail down her spine, pulling a shiver from his chosen mate.

“So pretty. Take me so good. Pretty Master,” Cu praises, digging his claws into her hips to speed her up, watching her breasts bounce with each thrust. She cries out as he digs his claws into her hips, dragging small scratches across them, letting them bleed. Cu lets out a loud, rolling purr at the sight of her blood dripping down her hips and thighs. He bucks his hips up into her, grinning at the moans and cries she lets out at the feeling.

“Oh fuck. Too much. I can’t. Lord,” Ritsuka chokes out, bouncing in time with his thrusts. Cu shifts to sit up, latching back onto her tit, sucking in most of the flesh before biting down, moaning at the taste of her blood. She screams, tightening around his cocks, twitching when he releases her tit to lap at the wound.

“Feel so good. Master. Mate. Mine, mine, mine,” he chants, wrapping his arms around her back to use it’s leverage to force her down on his knots again. Ritsuka moans loudly at the feeling of the knots going in and out of her as they slowly re-inflate, before she screams again when they lock inside her, orgasming around them while Cu refills her with his own cum. She twitches, her abdomen re-inflated from his cum, her mind blank from pleasure, not even realizing that tears are streaming down her face. Cu looks at her, breathing heavily as drool drips from the corner of his mouth.

“Beautiful,” he breaths.

* * *

4 Days into Rut (According to Calculations)

 

Mash is worried. No, that doesn’t really cover what she’s feeling. She’s terrified of what could have happened to make Ritsuka-sempai disappear for the past five days. Missing Sempai a day or two is normal, with how big Chaldea is and how many Servants are now here, but for no one to have seen her for five days is bad.

“None of the security cameras have caught her recently,” Da Vinci explains, her fingers flying over the keyboard as the screens flicker. Roman is right beside her, running over past footage to maybe get an idea of where she could be, just as worried as Mash is.

“Hang on… There! I found her!” He exclaims, pointing at a small screen. Mash and Da Vinci move over to see what the Doctor is pointing at. On the screen, Sempai struggles with a bunch of comforters and pillows, stumbling over to a door before giving it a few kicks. The door opens and she says something. There’s a pause where she looks confused before shrugging to the best of her ability and entering the room. Roman speeds the video along, with no sign of Sempai but a masculine arm pulling in and putting out a tray of food EMIYA leaves outside the door.

“Ah! We need to go get her!” Mash exclaims, running out of the control room while shifting into Servant form. Roman and Da Vinci calls after her, but she can’t stop. Sempai could be hurt, or bound, or something equally heinous, so Mash can’t afford to stop.

Sprinting down the halls, she barely registers the Cus following her curiously, nor how Merlin and Gilgamesh follow her, nor how Medb was storming toward her destination before she runs past. Skidding to a stop at the room’s closed entrance, Mash bangs her fist against the door urgently.

“SEMPAI!! ARE YOU OKAY?!” she yells, pausing to catch her breath and listen. When no one replies, Mash tries again, ignoring her audience.

“SEMPAI, PLEASE ANSWER!!” she yells. No one responses from inside the room, causing Mash to do the one thing that she as the Demi-servant can do. She over rides the room lock just as Roman and Da Vinci arrive.

“W-wait Mash. That room’s where-” Roman starts, only to choke at the sight that greets everyone. Laying on blood stained comforters and pillows is Sempai, covered in scratches, bitemarks, and bruises. Her naked body is curled on itself, facing toward one of the walls as her orange hair covers her face. The only thing even remotely reassuring about this is that Sempai is obviously breathing, which is why Mash takes a step into the rooms. A loud snarl nearly has her stumbling back out as Berserker Cu appears above Sempai, his body covering hers while he glares at the group beyond his door, his teeth bared to them while growling.

“E-easy there, Cu. We just wanted to make sure Ritsuka-chan is okay,” Roman tells the Berserker. Cu continues to glare at them, although he does stop growling, before his eyes fall down to Sempai as she seems to wake up. Mash feels her face heat up when Sempai rolls onto her stomach, piercing herself on Cu’s penises (which is bizarre, Mash swears she heard that men only have one) with a wanton moan and a soft cry of, “Mate.” Cu purrs at her, thrusting into her while pulling her up enough for everyone to see her breasts, heavier than before and lactating, and her abdomen, inflated like she is several months pregnant.

“Mate, my Master. Mine,” Cu growls into her bitten and bleeding shoulder, sinking his teeth back into the skin. Instead of screaming or crying, like Mash and the others expected, Sempai moans, petting his hair while pressing kisses against his forehead.

“Yours, my Berserker. Mate,” she coos back, gasping when he releases her shoulder only to moan when he presses a bloody kiss against her mouth. Finally finding her ability to think again, Mash quickly undoes the override, watching the door close as they start to fuck again. The hall is filled with silence, everyone watching the door with various expressions.

“Well, how is Master pregnant, or pregnant-like?” Merlin asks, breaking the silence to cause sputtering and flailing from the other Cus, Gilgamesh looking thoughtfully curious and Medb pouting.

“My Cu is a breeder, so during his Rut, the woman’s body behaves like they’re pregnant. Even going so far as to keep his cum in them to mimic pregnancy,” she explains before leaning against the door to whine, “That should be meeeeeee…” Mash sputters and covers her face, tensing when she felt a hand pat her shoulder.

“I’m sorry for not warning you in time,” Roman apologizes, continuing to pat her shoulder while she has to live with the image of Sempai taking two huge dog dicks and acting like a slut.


End file.
